Standard straight knitting needles generally range from 10 to 16 inches, being a narrow stiff shaft that tapers at one end and has a knob at the other end to prevent stitches from slipping off Straight knitting needles are known to be made of plastic, metal, casein, or wood. These needles are used in knitting to pull loops of string through one another. Needles come in the thickness from 0.75 mm to 25 mm and are commonly marked with U.S. or U.K. sizes that correspond to the mm thickness. The long narrow stiff shaft is not bendable and can therefore result in pain, tiredness and numbness from repeated motion of writs, hands, and fingers during the formation of loops in the knitting position that must accommodate to the long straight stiff knitting shaft as well as difficulty maneuvering comfortably while knitting in confined spaces and around surrounding obstacles.